1. Field of the Invention
The present invention relates to a portable electronic device such as a portable telephone having a speaker placed inside a cabinet.
2. Description of Related Art
Conventional portable telephones have a speaker for radiating incoming sound and voice from a telephoning partner and placed in a cabinet. A plurality of sound radiating holes for passing through sound waves from the speaker are provided in an area opposed to a front face of the speaker in the cabinet. A dustproof net is placed inside the cabinet in close contact with the front face of the speaker to prevent dust from entering into the speaker.
Recent portable telephones have been provided with hands-free function, which allows being on the telephone with a cabinet away from ears, for example, on a desk. A large output speaker is mounted in such a portable telephone.
In the portable telephones, sound of the speaker causes air to enter and exit through the sound radiating holes of the cabinet. Because the dustproof net is formed from nonwoven fabric or the like and has large flow resistance when air passes therethrough, the dustproof net vibrates as air enters and exits therethrough, and repeats clashes against the front face of the speaker, to thereby cause a problem of occurrence of rattle sound. This problem becomes significant particularly in the case of a large output speaker.
When the dustproof net is attached in close contact with an inner face of the cabinet, the dustproof net also repeats clashes against the inner face of the cabinet to thereby cause the problem of occurrence of rattle sound.
Accordingly, it has been proposed that when the dustproof net is attached in close contact with the inner face of the cabinet, a projection for pushing up the middle of the dustproof net is formed on the inner face of the cabinet to provide space between the inner face of the cabinet and the dustproof net, to thereby suppress occurrence of rattle sound (JP 2806847 B).
However, in the above-described conventional structure, there has been a problem of a complicated mold structure because the projection needs to be formed on the inner face of the cabinet.